Polarized latch relay

ABSTRACT

A polarized latch relay with an exceptionally strong holding characteristic in either latched condition. The relay comprises two permanent magnets, each between a respective pair of pole pieces; an armature pivotally supported apart from the permanent magnets and pole pieces with each of its ends disposed within a respective gap formed between extending end portions of each pair of pole pieces; and a core disposed between the permanent magnets and containing an electrically energizable coil wound thereon.

' United States Patent Inventors Andrew 0. Adams Inglewood; Roman J. Capol, Norwalk, both of Calif. Appl. No. 12,592 Filed Feb. 19, 1970 Patented Nov. 16, 1971 Assignee Leach Corporation South Pasadena, Calif.

POLARIZED LATCH RELAY 10 Claims, 3 Drawing Figs.

U.S. Cl 335/230, 335/ 1 70 Int. Cl l-l0lh 51/22 Field of Search... 335/230,

[56] References Cited UNITED STATES PATENTS 2,203,888 6/1940 Ashworth 335/234 2,941,130 6/1960 Fischer et al. 335/230 3,317,871 5/1967 Adams 335/230 3,470,510 9/1969 Richert 335/230 Primary Examiner-Harold Broome Attorney-Christie, Parker &. Hale ABSTRACT: A polarized latch relay with an exceptionally strong holding characteristic in either latched condition. The relay comprises two permanent magnets, each between a respective pair of pole pieces; an armature pivotally supported apart from the permanent magnets and pole pieces with each of its ends disposed within a respective gap formed between extending end portions of each pair of pole pieces; and a core disposed between the permanent magnets and containing an electrically energizable coil wound thereon.

PATENTEDHUY 1 3.621.419

SHEET 2 BF 2 POLARIZED LATCH RELAY BACKGROUND OF THE INVENTION 1. Field of the Invention This invention pertains to relays and more specifically, to latch relays employing permanent magnets.

2. Description of the Prior Art High-performance relays are required to withstand extreme amounts of shock and to operate under adverse conditions. Such relays are designed to meet or exceed requirement of an environment in which the vibration is typically 3,000 hertz, the shock and acceleration ratings exceed 50 times gravity, and the typical temperature operation range is from 70 to 120 C. Today, such a relay is required to be built in a space of only about 1 cubic inch.

Polarized latch relays generally include permanent magnets designed to hold a reciprocating armature at each end of its stroke. Various polarized latch relay configurations, operable in the above-described environment, have been devised and used heretofore.

Such known latch relays usually contain an armature pivotally mounted such that its pivot portion forms a line contact with either a permanent magnet or one or more pole pieces. Such pivot portion, therefore, takes on the magnetic polarity of that to which it is physically connected. Magnetic flux, therefore, passes out from the armature and through the line contact thereby establishing a relatively high-reluctance path with a consequent loss in holding characteristics.

When another predetermined portion of the armature contacts a pole piece thereby establishing one end of the armature stroke, it will be held there because of the flux produced by the permanent magnet associated with such pole piece. More specifically, the torque holding (latching) the armature in contact with the pole piece is directly proportional first to the magnetic force of attraction between the other predetermined portion of the armature and the associated permanent magnet and second to the length of the effective lever arm of the armature.

As used in this application, effective lever arm shall indicate the length of the armature between its pivot portion (fulcrum) and that other portion which contacts a pole piece (thereby establishing one end of the armature's stroke). The prior art latch relays have an effective lever arm less than the maximum attainable lever arm established when the other portion contacting a pole piece is at one extreme end of the armature. Such prior art latch relays have that other portion of the armature which touches a pole piece at some distance between an extreme end of the armature and its center pivot portion, thus reducing the effective lever arm to a value less than maximum.

The holding torque produced by such prior art latch relays is further minimized in value since the magnetic force produced by the pennanent magnet associated with the pole piece in contact with the armature is necessarily applied on only one side of the pivot portion at a time. There is no comparable magnetic force of attraction acting on the other side of the armature pivot portion in a manner so as to aid the force of attraction achieved on the one side. If anything, it operates to cancel the effective holding torque.

A typical prior art latching relay, as above alluded to, is more fully and completely described in US Pat. No. 2,941,130 issued to J. Fischer et al.

SUMMARY OF THE INVENTION The latch relay according to the present invention provides a very small compact latch relay with extremely strong holding characteristics. These strong holding characteristics are defined by the holding torque produced in a unique latch relay configuration consisting of a pair of permanently magnetizable elements, each associated with a pair of pole pieces arranged on either side of and in juxtaposition with such magnetizable element.

Each pole piece has an end portion extending past the associated magnetizable element such as to form a pair of gaps, one associated with each magnetizable element. An armature is pivotally supported with respect to the magnetizable elements and pole pieces such that its center is supported apart from the magnetizable elements and pole pieces, whereas each of its ends are disposed in a respective one of the pair of gaps. The resultant flux paths produce a couple formed with forces of substantially equal magnitude exerted in opposite directions at opposite ends of the armature. Thus, when the armature is at either end of its stroke, the holding torque, latching the armature at such end of its stroke, is proportional to the sum of the magnetic attracting forces normally exerted at either armature end.

The extremely strong holding characteristic, defined by the holding torques, is attained, therefore, because of three major factors:

1. The center pivot portion of the armature is disposed apart from the pole pieces and pennanent magnets. No flux can pass through and out the center pivot portion as in the case with the line contact pivot of the prior art latch relays. The attracting forces latching the relay at either end of the armature stroke, therefore, are not limited by any flux passing out the armature center pivot portion.

2. Since each armature end is disposed in a respective gap defined by a distinct pair of pole pieces respectively associated with a distinct permanent magnet, distinct forces attract each of the armature ends toward one pole piece of each pair in a manner such that a couple is formed. The effective force of attraction is thus the sum of the distinct forces.

3. Since each armature end constitutes that portion on each side of the pivot portion which is attracted toward a pole piece, theeffective lever arm is substantially at the maximum possible value (above defined). The torque causing the latching to occur, therefore, is thus maximized at each armature end with the resultant torque being the sum of the effective torques at each armature end-(since a couple has been formed).

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 shows in schematic manner the preferred embodiment of the polarized latch relay of the present invention with its armature in one latched position.

FIG. 2 shows the same embodiment of the polarized latch relay of FIG. 1 with the armature in its other latched position.

FIG. 3 is a perspective view of the latch relay of FIGS. 1 and 2 shown within a typical assembly.

DESCRIPTION OF THE PREFERRED EMBODIMENT The polarized latch relay of the present invention contains a pair of permanently magnetizable elements 10 and 12. Magnetizable element 10 is disposed between, and in juxtaposition with, pole pieces 14 and 16. Similarly, magnetizable element 12 is disposed between, and in juxtaposition with pole pieces 18 and 20. All four pole pieces and both magnetizable elements are aligned such that they have substantially parallel planar surfaces. Coils 22 and 24 are wound on core 26 which is disposed between and in juxtaposition with pole pieces 16 and 18. Accordingly, core 26 has parallel planar surfaces with the four pole pieces and two magnetizable elements. Furthermore, the alignment of the core 26 with the pole pieces and magnetizable elements is such that the longitudinal axis of core 26 is perpendicular to the longitudinal axes of both magnetizable elements and all four pole pieces.

Pole pieces 14 and 16, respectively, contain angularly ex tending end portions 28 and 30 which form a gap 32 therebetween. Similarly, pole pieces 18 and 20, respectively, contain angularly extending end portions 34 and 36 which form a gap 38 therebetween. Armature 40 is pivotally supported about point 42 by pivot bracket 41 made of nonmagnetic material, such that the armature center is apart from and not in contact with any other elements of the latch relay. Ends 44 and 46 of armature 40, however, are respectively disposed in gaps 32 and 38 for movement therein as the armature is rotatably moved about its pivot point 42.

In operation, pennanently magnetizable elements and 12 are permanently magnetized in opposing directions relative to the position of each other, such that pole pieces 14 and are, for example, south poles and pole pieces 16 and 18 are north poles. It is obvious, however, that the converse polar arrange ment could be used. Assume that armature end 46 is initially in contact with pole piece 20 at end portion 34 thereof. Such position is shown in FIG. 1. The following flux paths are, therefore, established prior to energization of the coils (hereinafter described): flux path A established by permanent magnet 10; and flux path B established by permanent magnet 12. These precoil-energization flux paths tend to retain the present armature position, i.e., the armature is latched in contact with pole piece 20 by reason of the magnetic attracting forces at either annature end established by flux path B (such forces and the resultant torque defined thereby are hereinafter fully described).

It should be noted at this point, that when the armature is latched at either end of its stroke, there are two forces responsible for so latching the armature. In FIG. 1, for example, flux path B produces a magnetic attracting force at point F1 and also produces a magnetic attracting force at F2. A couple is thus fonned about the armature pivot portion since the forces at F1 and F2 are exerted in opposite directions and are substantially equal in magnitude. It is obvious that the force of attraction at F3, produced by flux path A, is not sufficient to counteract the couple formed by attracting forces at F1 and F2.

It should also be noted that the forces produced at either armature end are defined by the mathematical relationship: F=B S/72=KB where F is the force, B is the flux density, S is the area through which the flux passes and is a constant, and K is a constant representing the value of S/72. Thus, the forces are each proportional to the square of the respective flux density.

It should further be noted that there are four alternative latched conditions in each latching position, i.e. at each end of the armature stroke. With reference to FIG. 1, for example, these four conditions are:

l. armature end 44 contacting pole piece end portion 30, and armature end 46 contacting pole piece end portion 34;

2. armature end 44 leaving a slight gap 45 between it and end portion 30 and armature end 46 contacting end portion 34 (such condition being the only one shown in FIG. 1);

3. armature end 44 contacting end portion 30, and armature end 46 leaving a slight gap between it and end portion 34; and

4. armature end 44 leaving a slight gap between it and end portion 30, and armature end 46 leaving a slight gap between it and end portion 34. This condition may occur if a pair of residual shims are fastened to either armature half at some distance between the extreme end and the pivot portion. Such is shown, for example, in FIGS. 1 and 4 of U.S. Pat. No. 2,941,130.

Whether a gap exists between either or both end portions is not significant from the standpoint of the attractive forces being produced at points F 1 and F2 to thereby form a couple. The fact that the gaps are optional, however, is significant in that it allows outer pole pieces 14 and 20 to be longitudinally adjusted prior to use in order to accommodate different types of latching motor armatures within the relay. More specifically, by adjusting the longitudinal position of pole pieces 14 and 20, the gaps between the armature ends and the pole pieces are varied. It should be obvious that an equivalent four conditions necessarily exists with regard to the other latching position shown in FIG. 2. With reference now to the exact latching condition shown in FIG. 1 (i.e. condition number 2, above), there are two coils 22 and 24 wound on core 26. The coils are selectively connectable to a voltage source 48 by ganged switches 50 and 52 and are so wound that the current through each flows in opposite directions. The flux produced by each, therefore, extends in opposite directions. It is obvious that a single coil could be used by selectively reversing the current direction therethrough. The use of two coils in the preferred embodiment of the present invention is, therefore, merely exemplary.

When it is desired to cause the armature to rotate into its other latched position, i.e., armature end 44 in contact with extending end portion 28 of pole l4, coil 22 is energized from voltage supply 48. The direction of current flow through the coil is such as to cause flux to extend along path C in the direction indicated. The flux from permanent magnet 12 (path B) and the flux from coil 22 (path C) thereby oppose each other. Correspondingly, the flux from permanent magnet 10 (path A) is supported by the flux from coil 22 (path C). Thus, the forces holding armature end 46 in contact with pole piece 20, i.e. the forces at F1 and F2, are substantially nullified; whereas the force tending to attract armature end 44 into contact with pole piece 14, i.e. the force at F3, is enhanced and the force tending to attract armature end 46 in contact with pole piece 18, i.e. the force at F4, is enhanced. The end result is that armature 40 is rotated about its pivot point 42 until its' end 44 comes in contact with pole piece 14 and its end 46 in contact with pole piece 18.

If coil 22 were deenergized at this point, armature end 44 would stay latched to pole piece 14 because of the holding forces at F2 and F1 established by the flux path produced and formed by permanent magnet 10 (path A of FIG. 2). Paths A and B of FIG. 2 are the exact converse of paths A and B of FIG. 1, i.e., flux emanating from magnet 12 will follow a path identical with path A of FIG. 1 and flux emanating from magnet 10 will follow a path identical to path B of FIG. 1. New flux paths A and B are clearly shown in FIG. 2.

If it is now desired to return armature 40 to the position shown in FIG. 1, coil 24 is energized by connection to voltage supply 48. The direction of current flow through coil 24 then causes flux to extend along path C in the direction shown in FIG. 2. Such flux opposes the flux produced by magnet 10 (path A) and adds to the flux produced by magnet 12 (path B). The forces at F2 and F1 usually holding armature end 44 to pole piece 14 are, therefore, substantially nullified; whereas the forces at F3 and F4, tending to attract armature end 46 and 44 into contact with pole pieces 20 and 16, respectively, is enhanced. The resultant rotation of armature 40 about its pivot point 42 causes armature end 46 to contact pole piece 20 and be held in contact therewith, after coil 24 is deenergized, by the resultant forces at F l and F2 (FIG. 1) produced by the flux from permanent magnet 12. The relay is thus latched in the latching position shown in FIG. 1.

An important aspect of the present invention resides in the high degree of holding torque attained in either latched position. This is a direct result of a couple being formed at the armature with forces of substantially equal magnitude being exerted in opposite directions at the armature ends (44 and 46). The couple is formed when either armature end is in contact with (or at a minimal gap away as above discussed) a respective pole piece (14 or 20 respectively) because of the resultant flux paths (A and B or A and B) established by the permanent magnets (10 and 12). The effective holding torque in each latched position is, therefore, directly proportional to the sum of the two forces at each armature end. The torque is further maximized since it is the armature ends that contact the pole pieces, thereby making maximum length lever arms at each half of the armature (torque being directly proportional to lever arm lengths). The result is an extremely strong holding torque in either latched condition. Lastly, the torque is not limited by any flux flowing out from the center of the armature which would thereby decrease the holding forces at each armature end, as in the prior art.

FIG. 3 shows the latch relay of FIGS. 1 and 2 within a supporting frame 54 designed to accommodate its practical use. Apertures 56, in housing 54, are designed to allow the position of the armature 40 relative to the pole pieces (FIGS. 1 and 2) to be inspected for possible adjustment of any of the gaps in the manner heretofore discussed. Armature 40 controls the position of blades 58 (partially obscured from view) which contain contact points 60 suitably secured thereon. Contact points 60 are located at either ends of blades 58 and are adapted to contact respective contact points on the underside of contacts 62 (such points being obscured from view). Contacts 62 are in turn coupled to those of contact pins 64 shown in FIG. 3 by means of angular bracket connector 66 (partially obscured).

A precise description of the contact blade assembly partially shown in FIG. 3 can be found in the description of FIGS. 1-3 in US. Pat. No. 3,484,729. It should be noted that such patent, however, deals with a different nonlatching motor as sembly, only the contact blade assembly and manner of housing the entire latch relay being similar. It should also be noted that other contact blade assemblies can be used with the present latch relay, such use being within the contemplation of the present invention.

In conclusion, what has been disclosed is a high-performance polarized latch relay exhibiting an exceptionally strong holding characteristic at either end of the armature s stroke.

What is claimed is:

1. A latch relay comprising:

a. a first permanently magnetizable element;

b. a first pair of pole pieces arranged on either side of and in juxtaposition with the first permanently magnetizable element and having extending end portions defining a first 8 p;

c. a second permanent magnetizable element;

d. a second pair of pole pieces arranged on either side of and in juxtaposition with the second permanently magnetizable element and having extending end portions defining a second gap;

e. an armature having first and second ends and being pivotally supported apart from the magnetizable elements and pole pieces with each end movably disposed in a respective one of the first and second gaps; and

f. a core fixedly disposed between and in juxtaposition with one pole piece from each of the first and second pairs of pole pieces.

2. The latch relay of claim I, in which the first and second permanently magnetizable elements and the core are aligned such that they have parallel planar surfaces with each other and with all of the pole pieces.

3. The latch relay of claim 2, in which the alignment of the core and permanently magnetizable elements is such that the longitudinal axis of the core is perpendicular with the longitudinal axes of each of the first and second permanently magnetizable elements.

4. The latch relay of claim 3, in which the extending end portions of the pole pieces of each pair are parallel and angularly displaced toward the other pair of pole pieces.

5. The latch relay of claim 4, in which the first and second permanently magnetizable elements are permanently magnetized in opposing directions relative to the location of each in the latch relay.

6. The latch relay of claim 5, in which each permanently magnetizable element is disposed between its respective pole pieces in such a manner that the longitudinal axis of each is perpendicular to the longitudinal axis of the core.

7. The latch relay of claim 6, further including:

a. electrically energizable coil means wound on the core;

and

b. means energizing the electrically energizable coil means such that the magnetic fiux produced thereby opposes the magnetic flux produced by one of the permanent magnets and supports the magnet fiux produced by the other permanent magnet.

8. The latch relay of claim 6, in which there are first and second latched positions and wherein:

a. the first latched position is defined by the first armature end being in contact with one of the first pair of pole pieces, and the second armature end being in contact with one of the second pair of pole ieces; and b. the second latched position is de ined by the first armature end being in contact with the other of the first pair of pole pieces and the second armature end being in contact with the other of the second pair of pole pieces.

9. The latch relay of claim 6, in which there are first and second latched positions and wherein:

a. the first latched position is defined by the first armature end being disposed a distance away from one of the first pair of pole pieces but at a larger distance away from the other of the first pair of pole pieces, and the second armature end being in contact with one of the second pair of pole pieces; and

b. the second latched position is defined by the first armature end being in contact with the other one of the first pair of pole pieces, and the second armature end being disposed a distance away from the other of the second pair of pole pieces but at a larger distance away from the one of the second pair of pole pieces.

10. The latch relay of claim 6, in which there are first and second latched positions and wherein:

a. the first latched position is defined by the first armature end being disposed a distance away from one of the first pair of pole pieces but at a larger distance away from the other of the first pair of pole pieces, and the second armature end being disposed a distance away from one of the second pair of pole pieces but at a larger distance away from the other of the first pair of pole pieces; and

b. the second latched position is defined by the first armature and being disposed a distance away from one of the first pair of pole pieces but at a smaller distance away from the other of the first pair of pole pieces, and the second armature end being disposed a distance away from one of the second pair of pole pieces but at a smaller distance away from the other of the first pair of pole pieces.

l l 4 I 

1. A latch relay comprising: a. a first permanently magnetizable element; b. a first pair of pole pieces arranged on either side of and in juxtaposition with the first permanently magnetizable element and having extending end portions defining a first gap; c. a second permanent magnetizable element; d. a second pair of pole pieces arranged on either side of and in juxtaposition with the second permanently magnetizable element and having extending end portions defining a second gap; e. an armature having first and second ends and being pivotally supported apart from the magnetizable elements and pole pieces with each end movably disposed in a respective one of the first and second gaps; and f. a core fixedly disposed between and in juxtaposition with one pole piece from each of the first and second pairs of pole pieces.
 2. The latch relay of claim 1, in which the first and second permanently magnetizablE elements and the core are aligned such that they have parallel planar surfaces with each other and with all of the pole pieces.
 3. The latch relay of claim 2, in which the alignment of the core and permanently magnetizable elements is such that the longitudinal axis of the core is perpendicular with the longitudinal axes of each of the first and second permanently magnetizable elements.
 4. The latch relay of claim 3, in which the extending end portions of the pole pieces of each pair are parallel and angularly displaced toward the other pair of pole pieces.
 5. The latch relay of claim 4, in which the first and second permanently magnetizable elements are permanently magnetized in opposing directions relative to the location of each in the latch relay.
 6. The latch relay of claim 5, in which each permanently magnetizable element is disposed between its respective pole pieces in such a manner that the longitudinal axis of each is perpendicular to the longitudinal axis of the core.
 7. The latch relay of claim 6, further including: a. electrically energizable coil means wound on the core; and b. means energizing the electrically energizable coil means such that the magnetic flux produced thereby opposes the magnetic flux produced by one of the permanent magnets and supports the magnet flux produced by the other permanent magnet.
 8. The latch relay of claim 6, in which there are first and second latched positions and wherein: a. the first latched position is defined by the first armature end being in contact with one of the first pair of pole pieces, and the second armature end being in contact with one of the second pair of pole pieces; and b. the second latched position is defined by the first armature end being in contact with the other of the first pair of pole pieces and the second armature end being in contact with the other of the second pair of pole pieces.
 9. The latch relay of claim 6, in which there are first and second latched positions and wherein: a. the first latched position is defined by the first armature end being disposed a distance away from one of the first pair of pole pieces but at a larger distance away from the other of the first pair of pole pieces, and the second armature end being in contact with one of the second pair of pole pieces; and b. the second latched position is defined by the first armature end being in contact with the other one of the first pair of pole pieces, and the second armature end being disposed a distance away from the other of the second pair of pole pieces but at a larger distance away from the one of the second pair of pole pieces.
 10. The latch relay of claim 6, in which there are first and second latched positions and wherein: a. the first latched position is defined by the first armature end being disposed a distance away from one of the first pair of pole pieces but at a larger distance away from the other of the first pair of pole pieces, and the second armature end being disposed a distance away from one of the second pair of pole pieces but at a larger distance away from the other of the first pair of pole pieces; and b. the second latched position is defined by the first armature and being disposed a distance away from one of the first pair of pole pieces but at a smaller distance away from the other of the first pair of pole pieces, and the second armature end being disposed a distance away from one of the second pair of pole pieces but at a smaller distance away from the other of the first pair of pole pieces. 